This page exposes the results of running answer tests on STACK test cases. This page is automatically generated from the STACK unit tests and is designed to show question authors what answer tests actually do. This includes cases where answer tests currentl fail, which gives a negative expected mark. Comments and further test cases are very welcome.

## EquivFirst

Test
?
Student response
Opt
Mark
EquivFirst
x
[x^2=4,x=2 or x=-2]
-1 ATEquivFirst_SA_not_list.
EquivFirst
[x^2=4,x=2 or x=-2]
x
-1 ATEquivFirst_SB_not_list.
EquivFirst
[1/0]
[x^2=4,x=2 or x=-2]
-1 ATEquivFirst_STACKERROR_SAns.
EquivFirst
[x^2=4,x=2 or x=-2]
[1/0]
-1 ATEquivFirst_STACKERROR_TAns.
EquivFirst
[x^2=4,x=2 or x=-2]
[x^2=4,x=2 or x=-2]
1 (EMPTYCHAR, EQUIVCHAR)
$\begin{array}{lll} &x^2=4& \cr \color{green}{\Leftrightarrow}&x=2\,{\text{ or }}\, x=-2& \cr \end{array}$
EquivFirst
[x^2=9,x=3 or x=-3]
[x^2=4,x=2 or x=-2]
0 ATEquivFirst_SA_wrong_start
The first line in your argument must be "$$x^2=4$$".
EquivFirst
[x^2=4,x=2]
[x^2=4,x=2 or x=-2]
0 (EMPTYCHAR,IMPLIEDCHAR)
$\begin{array}{lll} &x^2=4& \cr \color{red}{\Leftarrow}&x=2& \cr \end{array}$
EquivFirst
[x^2=4,x^2-4=0,(x-2)*(x+2)=0,x
=2 or x=-2]
[x^2=4,x=2 or x=-2]
1 (EMPTYCHAR, EQUIVCHAR, EQUIVCHAR, EQUIVCHAR)
$\begin{array}{lll} &x^2=4& \cr \color{green}{\Leftrightarrow}&x^2-4=0& \cr \color{green}{\Leftrightarrow}&\left(x-2\right)\cdot \left(x+2\right)=0& \cr \color{green}{\Leftrightarrow}&x=2\,{\text{ or }}\, x=-2& \cr \end{array}$
EquivFirst
[x^2=4,x= #pm#2, x=2 or x=-2]
[x^2=4,x=2 or x=-2]
1 (EMPTYCHAR, EQUIVCHAR, EQUIVCHAR)
$\begin{array}{lll} &x^2=4& \cr \color{green}{\Leftrightarrow}&x= \pm 2& \cr \color{green}{\Leftrightarrow}&x=2\,{\text{ or }}\, x=-2& \cr \end{array}$
EquivFirst
[x^2-6*x+9=0,x=3]
[x^2-6*x+9=0,x=3]
1 (EMPTYCHAR,SAMEROOTS)
$\begin{array}{lll} &x^2-6\cdot x+9=0& \cr \color{green}{\text{(Same roots)}}&x=3& \cr \end{array}$
EquivFirst
[x^2=4,x=2]
[x^2=4,x=2]
[assumepos]
1 (ASSUMEPOSVARS, EQUIVCHAR)
$\begin{array}{lll}\color{blue}{\text{Assume +ve vars}}&x^2=4& \cr \color{green}{\Leftrightarrow}&x=2& \cr \end{array}$